240 Sundancer 2000 Finding D+ on alternator

Holgersson

New Member
Feb 13, 2017
4
Loftahammar, Baltic Sea, Sweden
Boat Info
SeaRay 240 Sundancer 2000

Garmin 721xs
Engines
Mercruiser 5.0 EFI Bravo 3
Hi!

Sundancer 240 -00, Mercruiser 5.0 EFI Bravo 3.

The Swedish summer is coming and we’re getting ready to hit the water after a long cold winter.

Due to last seasons problems with our battery economy (two kids in the early teens demands ah ) I’m now getting a relay to separate the house batteries and the starting battery, before there was two batteries that were both house and starting in parallel. Now will we axpand the bank with a third.

Installing the relay is no problem, except for finding the D+ on the alternator, because the relay will only separate the house with the starting battery when the ignition is on. I Could wire on to the ignition switch, but I’m too lazy and it seems to unnecessarily to do that long wiring when I have all what I need in the engine bay.

At some forum the idea was the purple wire shown in picture, but on my alternator the purple wire is attached with a red/purple wire in a socket, no place for further attachment there?

I hope my Swedish kind of English not messed it up totally so you guys can make some sense out of it..

Take care!
 

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No idea about d+...


But I think you might have the wrong kind of relay. Your description of the relay you have seems to be backward to what’s needed and will allow a house load to drain all batteries if the ignition is off...

Ideally, only engine critical stuff should be wired to the start battery, and everything else should be wired to the house battery. Then fit a voltage sensitive relay between the + terminals of both battery banks - this will only combine them when the engine driven alternator has charged the start battery to a preset level to then begin charging the house batteries
 
i Assume your boat has a battery switch. Just isolate your house and starting batteries with your switch. If you run your house batteries down to the point the engine won’t start just flip your switch over to the starting battery.
 

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